Anaes · Airway management

Direct laryngoscopy & orotracheal intubation — blade types, Cormack-Lehane grade, BURP, ETT selection and confirmation

Also known as Direct laryngoscopy · Orotracheal intubation · Cormack-Lehane grade · Macintosh blade · Miller blade · BURP manoeuvre · Endotracheal tube · Murphy eye · Sniffing position

Direct laryngoscopy is the technique by which the larynx and vocal cords are brought into a single line of sight so that a tracheal tube can be passed under direct vision, and it remains the index skill of airway management against which every alternative is measured. The framework rests on six ideas: the geometry of the sniffing position aligns the oral, pharyngeal and laryngeal axes; the curved Macintosh blade (placed in the vallecula) and the straight Miller blade (placed behind the epiglottis) lift the tongue and epiglottis by different mechanisms; the Cormack-Lehane grade records the view obtained and a grade of three or four defines the difficult intubation; the BURP manoeuvre and optimal external laryngeal manipulation improve a poor view and are distinct from cricoid pressure; the endotracheal tube is chosen by cuff, size and design, with the Murphy eye protecting the right upper lobe; and intubation is confirmed by sustained waveform capnography, because an unrecognised oesophageal intubation is fatal. Anchored to contemporary evidence on the optimisation of intubating conditions, the physiological difficult airway, double-lumen tube practice, and the airway management of neuromuscular disease. Built on the Cormack-Lehane obstetric grading paper, the Knill BURP case report, the Adnet sniffing-position randomised study (n=456), the Difficult Airway Society 2015 unanticipated-difficult-intubation guidelines, the NAP4 major-complications audit (failure to use capnography in 74% of death-or-brain-injury cases), and the Lewis videolaryngoscopy-versus-direct Cochrane review (64 studies, 7,044 participants).